The invention relates first of all to a tensioning device for extending a threaded bolt by way of tension on the threaded end section thereof, having a supporting tube which surrounds the threaded end section, a cylinder which is arranged in an extension of the supporting tube and has at least one piston which can be moved therein in the longitudinal direction and can be connected to a hydraulic supply, an exchange socket which is configured such that it can be driven axially by the piston and is provided at its one end with an internal thread for screwing to the threaded end section and at its other end with an external polygon member, and a tool which can be attached releasably to the external polygon member in order to turn the exchange socket.
Furthermore, the invention relates to a tool which is intended for a tensioning device of this type and is preferably configured as a drive adapter.
A tensioning device of the generic type for threaded bolts is known from WO 2010/054959 A1. In order for it to be possible to check the length of that threaded end section of the threaded bolt which is gripped by the exchange socket, a slim measuring gauge is seated in the exchange socket in a longitudinally displaceable manner. The said measuring gauge is supported with its lower end against the end face of the threaded bolt to be tensioned. Its other end protrudes out of the exchange socket and is provided at this exposed end with a marking, using which it can be read off whether the threaded projection, that is to say the length of the threaded section which is gripped by the exchange socket, is sufficient for the tensioning process. In order to screw the exchange socket onto the threaded bolt, the tensioning device is rotated about its axis so that the exchange socket is screwed onto the free end of the threaded section of the threaded bolt.
As an alternative in connection with the tensioning device of WO 2010/054959 A1, there is the option, not disclosed however, to employ an external square, provided on the exchange socket anyhow and is located below the exposed pin end, for screwing the exchange socket onto the threaded bolt. An open-end or ring spanner could be attached theoretically to the square in order to rotate the exchange socket and thus to screw it with its internal thread arranged at the bottom onto the threaded bolt before the extension process can begin. In contrast, tools other than open-end or ring spanners would be less suitable since they threaten to damage the slim measuring gauge and the marking provided thereon.
In practice, in which frequently a multiplicity of similar tensioning processes have to be carried out one after another, the downtimes for tightening and subsequent releasing again of the exchange socket by means of an open-end or ring spanner would be time-consuming.
The invention is based on the object of shortening the downtimes which are associated with the individual tensioning process.